/*
 * Copyright (c) 2005, 2011, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */
/*
 * $Id: KeyInfo.java,v 1.7 2005/05/10 16:35:34 mullan Exp $
 */
package javax.xml.crypto.dsig.keyinfo;

import java.util.List;
import javax.xml.crypto.MarshalException;
import javax.xml.crypto.XMLCryptoContext;
import javax.xml.crypto.XMLStructure;

/**
 * A representation of the XML <code>KeyInfo</code> element as defined in
 * the <a href="http://www.w3.org/TR/xmldsig-core/">
 * W3C Recommendation for XML-Signature Syntax and Processing</a>.
 * A <code>KeyInfo</code> contains a list of {@link XMLStructure}s, each of
 * which contain information that enables the recipient(s) to obtain the key
 * needed to validate an XML signature. The XML Schema Definition is defined as:
 *
 * <pre>
 * &lt;element name="KeyInfo" type="ds:KeyInfoType"/&gt;
 * &lt;complexType name="KeyInfoType" mixed="true"&gt;
 *   &lt;choice maxOccurs="unbounded"&gt;
 *     &lt;element ref="ds:KeyName"/&gt;
 *     &lt;element ref="ds:KeyValue"/&gt;
 *     &lt;element ref="ds:RetrievalMethod"/&gt;
 *     &lt;element ref="ds:X509Data"/&gt;
 *     &lt;element ref="ds:PGPData"/&gt;
 *     &lt;element ref="ds:SPKIData"/&gt;
 *     &lt;element ref="ds:MgmtData"/&gt;
 *     &lt;any processContents="lax" namespace="##other"/&gt;
 *     &lt;!-- (1,1) elements from (0,unbounded) namespaces --&gt;
 *   &lt;/choice&gt;
 *   &lt;attribute name="Id" type="ID" use="optional"/&gt;
 * &lt;/complexType&gt;
 * </pre>
 *
 * A <code>KeyInfo</code> instance may be created by invoking one of the
 * {@link KeyInfoFactory#newKeyInfo newKeyInfo} methods of the
 * {@link KeyInfoFactory} class, and passing it a list of one or more
 * <code>XMLStructure</code>s and an optional id parameter;
 * for example:
 * <pre>
 *   KeyInfoFactory factory = KeyInfoFactory.getInstance("DOM");
 *   KeyInfo keyInfo = factory.newKeyInfo
 *      (Collections.singletonList(factory.newKeyName("Alice"), "keyinfo-1"));
 * </pre>
 *
 * <p><code>KeyInfo</code> objects can also be marshalled to XML by invoking
 * the {@link #marshal marshal} method.
 *
 * @author Sean Mullan
 * @author JSR 105 Expert Group
 * @see KeyInfoFactory#newKeyInfo(List)
 * @see KeyInfoFactory#newKeyInfo(List, String)
 * @since 1.6
 */
public interface KeyInfo extends XMLStructure {

  /**
   * Returns an {@link java.util.Collections#unmodifiableList unmodifiable
   * list} containing the key information. Each entry of the list is
   * an {@link XMLStructure}.
   *
   * <p>If there is a public subclass representing the type of
   * <code>XMLStructure</code>, it is returned as an instance of that
   * class (ex: an <code>X509Data</code> element would be returned as an
   * instance of {@link javax.xml.crypto.dsig.keyinfo.X509Data}).
   *
   * @return an unmodifiable list of one or more <code>XMLStructure</code>s in this
   * <code>KeyInfo</code>. Never returns <code>null</code> or an empty list.
   */
  @SuppressWarnings("rawtypes")
  List getContent();

  /**
   * Return the optional Id attribute of this <code>KeyInfo</code>, which
   * may be useful for referencing this <code>KeyInfo</code> from other
   * XML structures.
   *
   * @return the Id attribute of this <code>KeyInfo</code> (may be <code>null</code> if not
   * specified)
   */
  String getId();

  /**
   * Marshals the key info to XML.
   *
   * @param parent a mechanism-specific structure containing the parent node that the marshalled key
   * info will be appended to
   * @param context the <code>XMLCryptoContext</code> containing additional context (may be null if
   * not applicable)
   * @throws ClassCastException if the type of <code>parent</code> or <code>context</code> is not
   * compatible with this key info
   * @throws MarshalException if the key info cannot be marshalled
   * @throws NullPointerException if <code>parent</code> is <code>null</code>
   */
  void marshal(XMLStructure parent, XMLCryptoContext context)
      throws MarshalException;
}
